1. Field of the Invention
This invention relates to flotation apparatus for processing mineral pulps or other types of slurries. Flotation chemicals and air are mixed with the pulp, slurry or other liquid-solids mixture to selective separate a solid material, or particular ones of several solid materials, from the pulp by a flotation process. Flotation processes involve the selective adherence of solids particles on gas or air bubbles which particles are lifted by the raising bubbles for removal from adjacent the top or other outlet within the flotation machine tank.
2. Description of the Prior Art
Most flotation machines have a single or multiple unit construction wherein a rotor having relatively short blades is rotated within a tank to pump and circulate pulp within the tank and include an air supply means in the form of a hollow tube associated with the impeller and a surrounding fixed stator. Typically of these are those shown in U.S. Pat. No. 2,243,309 where an apertured flat plate having radial upstanding blades is provided; U.S. Pat. No. 1,881,412 where 90.degree. depending rectangular radial blades are shown; and U.S. Pat. Nos. 3,843,101; 3,882,016; and 4,062,526 where blades of various lengths are on both sides of an impeller plate, extend radially over only the outer periphery of a flat plate and are spaced 22.5.degree. apart. A portion of the lower blade in the '016 patent extends below the stator bottom. U.S. Pat. No. 2,875,897 shows bar type impeller legs and a stator (FIG. 6) having parallel-sided passages; U.S. Pat. No. 4,265,739 has upstanding radial blades on an outer plate periphery; U.S. Pat. No. 3,491,880 shows a one piece radial star-like rotor and a one-piece stator; and U.S. Pat. No. 3,647,066 shows depending blades on a flat plate outer periphery with a surrounding stator. This latter patent discloses structures which are similar to the prior art marked as such in the attached drawings and represent commercial flotation machines now being manufactured and sold by applicant's assignee under the trademark "Agitair".